Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare this is a non-destructive write (readOnlyHint=false, destructiveHint=false, idempotentHint=false). The description adds genuine behavioral context beyond that: the note is durable and injected into every future conversation, which tells the agent the effect persists globally rather than being scoped to a timeline. It does not mention permissions, rate limits, or how to remove a standing note, so not a 5.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two tight sentences with zero filler. The core purpose and the sibling distinction are both front-loaded, and every clause carries information the agent needs.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple two-parameter write tool with no output schema and annotations covering the safety profile, the description is nearly sufficient: purpose, persistence behavior, and sibling distinction are all clear. The only gap is the unexplained 'tags' parameter, which leaves an agent guessing about categorization.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 0% for both parameters. The description conveys what 'text' should contain through examples (a standing preference, ongoing illness, travel, milestone), partially compensating. However, the optional 'tags' parameter is never mentioned in the description, so half the schema remains undocumented.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (Save) and resource (durable note) with an explicit scope: 'for Luna to recall in every future conversation with this family.' It also names the sibling log_note and states what this tool is not, so an agent can distinguish it without opening either schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly contrasts with log_note: 'this isn't a timeline event, it's context injected into future answers.' It also enumerates the kinds of content that belong here (standing preference, ongoing illness, upcoming travel, milestone), giving the agent a clear condition for selecting this tool over its closest alternative.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.